V. V. Kerzhanovich

Models of the structure of the atmosphere of Venus from the surface to 100 kilometers altitude

From a critical comparison and synthesis of data from the four Pioneer Venus Probes, the Pioneer Venus Orbiter, and the Venera 10, 12, and 13 landers, models of the lower and middle atmosphere of Venus are derived. The models are consistent with the data sets within the measurement uncertainties and established variability of the atmosphere. The models represent the observed variations of state properties with latitude, and preserve the observed static stability. The rationale and the approach used to derive the models are discussed, and the remaining uncertainties are estimated.

Preliminary results on the Venus atmosphere from the Venera 8 descent module

Abstract The Venera 8 descent module measured pressure, temperature, winds and illumination as a function of altitude in its landing on July 22, 1972, just beyond the terminator in the illuminated hemisphere of Venus. The surface temperature and pressure is 741 ± 7°K and 93 ± 1.5kgcm −2 , consistent with early Venera observations and showing either no diurnal variation or insignificant diurnal variation in temperature and pressure in the vicinity of the morning terminator. The atmosphere is adiabatic down to the surface. The horizontal wind speed is low near the surface, about 35m/sec between 20 and 40km altitude, and increasing rapidly above 48km altitude to 100–140m/sec, consistent with the 4-day retrograde rotation of the ultraviolet clouds. The illumination at the center of the day hemisphere of Venus is calculated to be about 1% of the solar flux at the top of the atmosphere, consistent with greenhouse models and high enough to permit photography of the Venus surface by future missions. The attenuation below 35km altitude is explained by Rayleigh scattering with no atmospheric aerosols; above 35km there must be substantial extinction of incident light.

Venera 8: Measurements of Temperature, Pressure and Wind Velocity on the Illuminated Side of Venus 1

Abstract Measurements of the temperature, pressure and wind speed in the atmosphere of Venus are reported. These were obtained with the interplanetary station Venera 8, which was the first entry probe to telemeter data from the solar-illuminated side of Venus. One component of the horizontal wind velocity was obtained, for the direction from the landing site to the sub-Earth paint,σ25° from the zonal direction. This component was found to decrease from σ100 m sec−1 at an altitude of 50 km to σ0 at the ground, with the direction of flow from the day side of the planet toward the night side at all altitudes.

Soft Landing of Venera 7 on the Venus Surface and Preliminary Results of Investigations of the Venus Atmosphere

Abstract A soft landing on the planet Venus was successfully accomplished by the automatic interplanetary station Venera 7. The temperature of the Venus atmosphere was measured during the descent and at the surface after landing. The variation of temperature and pressure with altitude on Venus was determined down to the surface by combining the temperature measurements with descent velocity derived from the Doppler shift data during the descent, and by considering the data collected previously during the flights of Veneras 4, 5 and 6.

Data on dynamics of the subcloud Venus atmosphere from Venera Spaceprobe measurements

Abstract This paper presents the principal results of wind velocity and turbulence measurements in the Venus atmosphere during the Venera flights. Based on one-way Doppler measurements wind estimations were obtained as a difference of the measured and computed descent velocity values. The computation of free parachute descent velocity was performed by an independent method that utilized aerodynamics of the spaceprobes and the pressure-temperature measurements of the Venus atmosphere. Entry point location, dynamics of the parachute-spaceprobe system as well as frequency instability of the on-board crystal oscillators are basic factors which influenced the accuracy of wind and turbulence estimations. Venera 4 measured a strong wind (up to 40–50 m sec −1 ) and turbulence at 0.7–4 bar levels (40–50km altitude); within the measurement errors neither wind nor turbulence were found at altitudes lower than 40 km. Venera 5 and Venera 6 Doppler data indicated very smooth velocity changes during the whole descent without noticeable signs of turbulence. Venera 7 measured a zonal wind component; values 5–14 m sec −1 were obtained at 38–53 km altitudes; below 38 km the wind velocity was zero. Estimation of wind velocity near the planet surface (0–3.5 km) leads to value of 0–2.5 m sec −1 . Based on an analysis of the apparatus construction characteristics and the radio signal variation during impact upon the Venus surface, values of 2–80 kg cm −2 were obtained for the bearing strength of the soil.

Venera 11 and Venera 12: Preliminary evaluations of wind velocity and turbulence in the atmosphere of Venus

Data accumulated from venera 4–10 have revealed unusual properties of the troposphere of Venus. This data has not been sufficient, however, to enable a complete description and account of these properties. Essential supplementary data has now been obtained from experiments carried out on Venera 11 and 12. These results, which are descibed in this paper, indicate that the atmosphere of Venus encompasses a strong. nonuniform, zonal movement which reveals a new type of circulation of the deep atmosphere.

On the wind-velocity measurements from Venera spacecraft data

Abstract Some features of the wind-velocity determination based on the results of Doppler shift measurements from the Venera probes during their descent in the Venus atmosphere are discussed. The validity of assumptions used in the reduction and analysis of these data are treated in connection with the preceding paper by Ainsworth and Herman. We conclude that the Venera velocity profiles are a valid representation of Venus atmospheric conditions.